1. Field of the Invention
The present invention relates to a galvano-mirror used in e.g. an optical disk apparatus for reflecting light in a desired direction. The present invention also relates to a method of making such a galvano-mirror.
2. Description of the Related Art
A conventional galvano-mirror is disclosed in JP-A-8(1996)-211320, for example. As shown in FIGS. 25A-25B of the accompanying drawings, the conventional galvano-mirror includes a mirror plate 8 and two driver plates 9A-9B. The mirror plate 8 is provided with a pivotable member 81 upon which a mirror 80 is mounted, and with a frame 83 to support the pivotable member 81 via two aligned torsion bars 82. The driver plate 9A is provided with a pair of electrodes 90a, 90b facing the pivotable member 81. Similarly, the other driver plate 9B is provided with a pair of electrodes (not shown) facing the pivotable member 81. For allowing the passage of light traveling to and from the mirror 80, the driver plate 9B is formed with an opening 91.
To rotate the pivotable member 81 in the N1-direction shown in FIG. 25B, the electrode 90a of the plate 9A and the non-illustrated counterpart electrode of the plate 9B are charged to e.g. a negative potential, while the electrodes (not shown) formed on the pivotable member 81 are charged to a positive potential. As a result, an electrical attracting force is generated between the pivotable member 81 and each of the driver plates 9A, 9B, thereby giving rise to the desired rotational movement. To rotate the pivotable member 81 in the opposite direction, the electrode 90b of the plate 9A and the counterpart electrode of the plate 9B are charged to a negative potential. By rotating the pivotable member 81 in this manner, it is possible to control the direction of the light reflected on the mirror 80.
Conventionally, to produce a plurality of galvano-mirrors of the above-described type, the components (such as a mirror plate 8 and driver plates 9A-9B) for one galvano-mirror are prepared separately from the components for another galvano-mirror, and then assembled. In this manner, however, the assembling procedure tends to become complicated, whereby the production efficiency will be unduly lowered. Further, the separate preparation of the components makes it difficult to preparing identical counterpart components of the respective galvano-mirrors.
The present invention has been proposed under the circumstances descried above. It is, therefore, an object of the present invention to provide a fabrication method enabling efficient production of high-quality galvano-mirrors.
Another object of the present invention is to provide galvano-mirrors made by such a method.
According to a first aspect of the present invention, there is provided a method of making a galvano-mirror which is provided with a mirror plate and at least one driver plate. The mirror plate includes a pivotable member upon which reflecting means and a first electrode are provided, while the driver plate includes a second electrode facing the first electrode. The method includes the steps of: preparing a first material substrate formed with a plurality of mirror plate regions each of which corresponds in arrangement to the mirror plate; preparing a second material substrate formed with a plurality of driver plate regions each of which corresponds in arrangement to the driver plate; attaching the first and the second material substrates so that each of the mirror plate regions faces a relevant one of the driver plate regions; and dividing the attached first and second material substrates into individual galvano-mirrors.
Preferably, each of the first and the second material substrates is a silicon wafer.
In a preferred embodiment of the present invention, the method may further include the steps of preparing a third material substrate provided with a plurality of driver plate regions, and positioning the first material substrate between the second and the third material substrates.
Preferably, the method may further include the steps of forming ribs on at least either one of the first and the second material substrates, and fixing the first and the second material substrates to each other via the ribs. In this case, the ribs may be halved at the step of dividing the attached first and second material substrates.
Preferably, each of the mirror plate regions includes a non-etched flat area in which the reflecting means is provided.
In a preferred embodiment of the present invention, the dividing of the attached first and second material substrates may be performed so that the mirror plate and the driver plate differ in size in each of the individual galvano-mirrors.
Preferably, the method may further include the step of forming a terminal connected to the first electrode in each of the mirror plate regions. In this case, the dividing of the attached first and second material substrates is performed so that the terminal is partially exposed from the driver plate in each of the individual galvano-mirrors. For the partial exposure of the terminal, a predetermined portion of each driver plate region may be etched away.
In a preferred embodiment of the present invention, the method may further include the step of forming a through-hole in at least either one of the first and the second material substrates for electrical connection. In this case, the method may further include the steps of forming a circular projection adjacent to the through-hole in at least either one of the first and the second material substrates, and filling the through-hole with a conductive material.
The method may further include the step of forming ribs on at least either one of the first and the second material substrates for separating the substrate regions from each other.
Preferably, the circular projection and the ribs are formed simultaneously by a thin layer forming technique.
Preferably, the method may further include the step of forming a stopper to prevent the pivotable member from pivoting in each of the mirror plate regions of the first material substrate. The stopper may be removed at the time of dividing the attached first and second material substrates.
According to a second aspect of the present invention, there is provided a galvano-mirror which includes: a mirror plate provided with a pivotable member upon which reflecting means and a first electrode are provided; and at least one driver plate provided with a second electrode facing the first electrode. Advantageously, the mirror plate and the driver plate differ in length from each other.
According to a third aspect of the present invention, there is provided a galvano-mirror which includes: a mirror plate provided with a pivotable member upon which reflecting means and a first electrode are provided; and a driver plate having an inner surface facing the mirror plate and an outer surface opposite to the inner surface. The inner surface is provided with a second electrode facing the first electrode, while the outer surface is provided with a plurality of external connection terminals. Advantageously, the driver plate is formed with a plurality of through-holes for connecting each of the first and the second electrodes to a relevant one of the external connection terminals.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.